Studies on some ternary complexes of copper(II) involving an amino penicillin drug

Abstract

Multiple equilibrium studies by pH-metric measurements in the ternary copper(II) complexes with ampicillin(amp) as ligand A and glycine(gly), dl-2-aminobutanoic acid(2aba), dl-3-aminobutanoic acid(3aba), 1,2-diaminopropane(dp), 1,3-diaminopropane(tp), dl-2,3-diaminopropanoic acid(dapa), dl-2,4-diaminobutanoic acid(daba) &dl-2,5-diaminopentanoic acid(ornithine)(orn) as ligands B show the presence of CuABH, CuAB or CuAH−1 B ternary complex species. In the CuAB species the binding of the ligands A and B is similar to their binding in their respective binary complexes. In CuABH−1 species the deprotonation occurs with amp(A) ligand. The ΔlogK values indicate higher stabilities for the ternary complexes than the binary species. The CuAB species with B=gly, 2aba, dapa & orn have been isolated and characterized. The conductivity measurements indicate that the complexes are non-electrolytes. Magnetic susceptibility and electronic spectral data suggest a square pyramidal geometry for CuAB with B=gly/2aba complexes and distorted octahedral geometry for CuAB with B=dapa/orn. The vibrational spectra are interpreted to find the mode of binding of ligand to metal. The TG/DTA studies reveal that the complexes decompose in three steps, indicating non-involvement of hydrated or coordinated water molecules in the complex. The cyclic voltammograms indicate a quasi reversible Cu2+/Cu+ couple. The antimicrobial activity and CT-DNA cleavage ability of the complexes show higher activity for ternary complexes.